As a method of administering a drug to a human body, oral administration and transdermal administration are often used. Although injection is a typical transdermal administration method, it is a procedure which takes time, is painful, and further is likely to cause an infection, so many people do not welcome the procedure. In contrast, a transdermal administration method without pain using a microneedle array has been recently attracting attention (Patent Document 1, Non-Patent Document 1).
In transdermal administration of a drug, skin stratum corneum works as a barrier to drug permeation, so only applying the drug on a skin surface does not necessarily cause enough permeability. In contrast, perforation of the corneum by using a minute needle, i.e. a microneedle can remarkably improve drug permeation efficiency compared to the application method. An article in which a large number of the microneedles are integrated on a substrate is a microneedle array. Furthermore, a product in which sheets such as an adhesive sheet for adhering the microneedle array to a skin or a protective release sheet for protecting and supporting the adhesive sheet when applying the microneedle array to a skin are added to the microneedle array in order to facilitate its use is called a microneedle patch. Herein, an adhesive sheet means a film, a fabric, or a paper to which an adhesive agent is applied.
When the microneedle is produced by using a substrate such as saccharide which disappears by metabolism in a body, an accident does not occur even if the needle is broken and remains in a skin. Furthermore, if a drug is contained in the saccharide, the drug can be easily administered into and under the skin by dissolving the inserted microneedle in the body (Patent Document 2).
However, since a skin is generally flexible, the microneedles cannot be easily inserted into the skin only by pressing the microneedle array with a finger when the microneedle array is administered to the skin. This is because a skin is elastic tissue originally with a role of defending various stimuli, impact, and the like from the outside world, so even if sharp tips of the microneedles are pressed against the skin, the skin absorbs the impact and deforms to prevent the entry of the microneedles into the skin.
For administering the microneedle array to a skin with the impact absorption capability, the microneedle array must be administered to the skin at high speed and with impact. As the method of the administration, utilization of a spring (Patent Documents 3-8), air pressure (Patent Document 7), magnetic force (Patent Document 9), or the like has been hitherto proposed. In order to make the spring easily usable for a woman or an infant, ingenuity is needed for a spring compression method and a trigger method. Also, the utilization of an pressure or magnetic force is not always simple. The conventional microneedle army administration devices still have practical problems, so a simpler device with which insertion can be surely performed has been demanded by users.